Eastern tree frogs are usually bright green. But scientists recently discovered darker green and black frogs living in Chernobyl’s radioactive zone. The animals have extra melanin—a dark-colored pigment—in their skin. It soaks up and scatters the radiation’s energy, which could protect the frogs from exposure.
This discovery is evidence of natural selection—the process by which organisms adapt over time, says Pablo Burraco. He’s a biologist at the Doñana Biological Station in Spain who led the study. Frogs born with more melanin had a better chance of surviving and passed this trait on to future generations.